The pump is used to transfer fluid, especially the liquid. In the Flow Injection Analysis (FIA), the most broad used is the peristaltic pump, which is a dynamic analysis that can analyze the tested materials without waiting for complete reaction. The advantages of the peristaltic pump are that it not only could provide steady and continuous fluid driving, but is cheap, simple to operate and easy to change the tube. Such properties are appropriate for the industries in need of precise liquid supplying, such as the pharmaceutical industry, the electronics industry, the environmental analysis, the medical apparatus, the biochemical experiment, and the cell culture, etc.
The peristaltic pump plays a very important rule in each field described above. By the different driving modes the peristaltic pump can be classified to the diaphragm peristaltic pump, the thermopneumatic peristaltic pump, and the hose compressed peristaltic pump. The membrane peristaltic pump needs complex manufacture and the production cost thereof is expensive; the thermopneumatic peristaltic pump drives fluid by the different heat, but some fluids are not appropriate in this way; the hose compressed peristaltic pump drives fluid by compressing the hose which has a lower production cost compared to the above two modes and is the mostly used.
Now, the peristaltic pumps in the market are usually very big in volume, e.g. EYELAMP-3N has 12 cm long, 13 cm wide, and 18.6 cm high and has 3 kg weight, and further it costs almost thousand US. Although these kinds of peristaltic pumps have multiple functions, but for the medical apparatus and biochip applications, they need neither so many functions nor so big flow volume and speed. Oppositely, what these industries need is a peristaltic pump which can easily and stably drive the fluid to flow forward, reverse, and stop. It is what the new-style peristaltic pumps want to achieve. Moreover, if the new peristaltic pump can be so cheap, easy to compose, slight for carry, and save power, the application fields will be much broader. However, the conventional peristaltic pumps cannot achieve all the requirements described above simultaneously, so the investigation of the present invention has been promoted.
The working theory of the hose compressed peristaltic pump uses two motions, compressing and releasing the hose, to drive the liquid. The conventional peristaltic pump compresses the liquid filling hose through the wheels. The hose between the two wheels are filled with the liquid, and therefore, when the wheels roll and change the compressing positions, the liquid in the hose is pushed to another position. When the wheels release the hose, the hose will restore to the pipe shape and the hollow condition to produce a vacuum attraction so as to discharge the liquid. As above, it is known that the hoes compressing peristaltic pump uses the wheels to compress and release the hose to produce a vacuum attraction so as to drive the liquid.
Please refer to FIG. 1, which is a conventional passive planet rolling pump. The pump comprises a pump head 1, and the hose 2 surrounds the pump head 1 and is compressed thereby. Additionally, the pump head 1 has a rotor 12 in the center for accepting the rolling of a motor (not shown) and a turntable 10 with plural wheels 14. The peristaltic pump uses the wheels 14 to compress the hose 2 to form a liquid storage space 20 between two wheels 14a and 14b. The turntable 10 rolling makes the wheels 14 orbit and change the compressing position in the hose 2, and also makes the liquid storage space move in the hose 2. When the wheel 14b orbits and moves toward the wheel 14c, the wheel 14b will release the hose 2. The hose 2 will restore and produce a vacuum attraction to make the liquid in the liquid storage space 20 move toward the transportation direction A. By the conventional pump in FIG. 1, each wheel 14 is passively rolled by the resistance of the hose 2 to compress the hose 2 smoothly and push the liquid forward. Moreover, in the miniaturized hose compressed peristaltic pump, because the pump drives less liquid, it only needs the small size hose 2, which results in the small size of the turntable 10 and the wheel 14. Therefore, the size of the wheel 14 is too small, i.e. the diameter of the wheel 14 reduces a lot, which also means the strength distance is shirt, so the strength applied on the wheel 14 surface should be very big to achieve enough torque. Nevertheless, the resistance between the hose 2 and the wheel 14 is not sufficient and the wheel 14 with the small diameter has too short strength distance to get enough torque to make the wheel roll. So the miniaturized peristaltic pump combined with the small hose usually has the problem that the wheel is not rolling and just slides and rubs the hose. Therefore, in the miniaturized peristaltic pump, the wheel has almost no function, but the cost and the assembling difficulty are increased.
The description above shows that it urgently needs a lightweight, miniaturized, low-cost, and easily-assembled hose compressed peristaltic pump, which still has the forward and reverse flow driving function.